The Japanese electric utility that owns the flaming GE reactors is considering asking military helicopters to spray water on the apparently boiling pool that holds some of the spent fuel rods. If it is boiling, the water would evaporate, exposing the highly radioactive rods to the air. They could then catch fire themselves, perhaps even exploding. Much more radiation would be released. NB: the idea of dropping water from helicopters might indicate a fear that things may otherwise be out of control.